JPH0822144A - Resin composition for toner and the toner - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. for obtaining a toner hard-block, excellent in anti-offsetting property, property of preventing the stain of a white surface and low-temp. fixability and excellent in the stability of an image even in the case of use in a copying machine over a long period of time. CONSTITUTION:This resin compsn. is based on a vinyl copolymer contg. a low polymer component crosslinked with a di(meth)acrylate cross-linking agent obtd. from >=5C straight. chain diol with <=1C branched chain and having the peak of mol.wt. within the range of 4X10<3>-8X10<4> in the mol.wt. distribution and an uncrosslinked high polymer component having the peak of mol.wt. within the range of 1X10<5>-4X10<6>. The vinyl copolymer has constituent. units of a styrene monomer and a (meth)acrylic ester monomer and/or other vinyl monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a toner used in electrophotography and the like, and more particularly to a resin composition for a toner used in a so-called dry development system and a toner.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, a photoconductive substance is used to form an electrical latent image on a photoconductor by various means, and the latent image is developed with a toner, and then necessary. Depending on the method, there is a method of obtaining a permanent visible image by transferring to a transfer material such as paper and then fixing with a heat source such as a heat roll.

A dry developing method is often used as a method for developing an electrostatic image in the electrophotographic method as described above. In the dry developing method, a toner in which a coloring agent such as a dye or a pigment is dispersed in a resin is used. And a two-component fine powder developer containing a carrier made of iron powder or glass beads,
Alternatively, a one-component type fine powder developer using a magnetic toner in which magnetic particles such as magnetite are dispersed in the toner is used.

In the dry developing system, the toner charged by friction is attached to the electrostatic latent image on the photosensitive member by an electric attraction, whereby a toner image is formed. Next, the toner image on the photoconductor is transferred to the fixing sheet, and then the transferred toner is fixed to the fixing sheet to form a permanent visible image.

The fixing method is carried out by pressing the toner image of the fixing sheet onto the surface of a heating roller having a surface formed of a material having a releasing property for the toner and passing the fixing sheet. The so-called heating roller method is often used.

In the heating roller method, there is a demand for a toner resin composition which can be fixed at a lower temperature in order to improve the economical efficiency such as power consumption and to increase the copying speed. To improve low-temperature fixability, a resin composition for a toner, which contains a vinyl-based copolymer as a main component and has a low molecular weight, has been proposed. However, although the low-temperature fixability of the toner is improved, a part of the toner that forms an image at the time of fixing is transferred to the surface of the heating roller, and the toner is transferred to the next sheet to be fed again to stain the image. (Offset phenomenon) is likely to occur, and the toner is likely to aggregate.

For the purpose of solving these problems, as a resin for toner, a resin composition comprising a low molecular weight polymer component and a high molecular weight polymer component (JP-A-56-158340).
However, since the low-molecular weight material is brittle, the toner fixed on the paper is liable to cause cohesive failure and stain on a white background.

Further, in the developer toner, a charge control substance such as a dye or a pigment is added to control the triboelectric chargeability. This charge control substance imparts a positive charge or a negative charge to the toner, and is disclosed in JP-B-41-20153, JP-B-44-6397, and JP-A-53-127.
No. 726 and Japanese Patent Laid-Open No. 57-141452.

The performance of these charge control substances as the charge control agent of the toner is sufficient, but the dispersibility in the resin is not sufficient. Therefore, the toner obtained by using the charge control substance is not always satisfactory in high image quality and stability due to running.

In recent years, personalization has progressed in the copying field,
In particular, there is an increasing demand for higher image quality and higher durability, and therefore resins for toners are also required to have performance suitable for higher image quality and higher durability.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to eliminate the drawbacks of conventional resin compositions for toners and toners, to obtain high-quality images, and in the case of using a copying machine for a long period of time. It is an object of the present invention to provide a resin composition for a toner and a toner, which are excellent in image stability and are also excellent in non-aggregation property, anti-offset property and anti-white background property.

[0012]

The present invention has been conceived in order to achieve the above object, and the resin composition for a toner according to the present invention mainly comprises a vinyl-based copolymer. A resin composition for a toner as a component, wherein the vinyl-based copolymer is crosslinked, and a low polymer component having a maximum molecular weight at a low molecular weight, and a non-crosslinked and high molecular weight A high polymer component having a maximum molecular weight, wherein the low polymer component has a straight chain having 5 or more carbon atoms,
And has no branched chain or is crosslinked with a crosslinking agent composed of diacrylate or dimethacrylate obtained from a diol having 1 or less carbon atoms in the branched chain, and the maximum molecular weight in the molecular weight distribution is 4 × 10 ³ to 8 × is in the range of 10 ^4, in the range molecular weight maximum value is 1 × 10 ⁵ to 4 × 10 ⁶ in molecular weight distribution of the high polymer component, wherein the vinyl copolymer is mainly composed of styrene monomer age,
A resin composition for a toner, comprising a (meth) acrylic acid ester monomer and / or a vinyl monomer as a constituent unit.

Further, in the invention described in claim 1, as the cross-linking agent, for example, as described in claim 2, a diamine obtained from a diol having a straight chain of 5 or more carbon atoms and having no branch chain is used. It may be acrylate or dimethacrylate, or as described in claim 3, a diacrylate or dimethacrylate obtained from a diol having a straight-chain aliphatic alkyl group having 5 or more carbon atoms and having no branch chain. May be

Further, the toner obtained by the present invention is characterized by containing the resin composition for a toner according to the invention described in claims 1 to 3 and a colorant as main components.
Hereinafter, details of the resin composition for a toner and the toner of the present invention will be described.

The resin composition for a toner according to the first aspect of the present invention contains a vinyl-based copolymer as a main component. Further, the vinyl-based copolymer contains a low polymer component having a maximum molecular weight at a low molecular weight and a high polymer component having a maximum molecular weight at a high molecular weight in the molecular weight distribution.

In the present invention, the strength of the toner resin is increased by cross-linking the low polymer having the maximum molecular weight in the low molecular weight, thereby improving the white background stain resistance. Further, by cross-linking the low polymer component, the molecular weight distribution of the low polymer component is broadened, thereby facilitating uniform dispersion of the low polymer component in the high polymer component. There is. As a result, the charge control agent can be dispersed more uniformly, and the image stability can be improved.

Further, the cross-linking agent has a straight chain having 5 or more carbon atoms. That is, the low polymer component is gently crosslinked by the relatively long chain crosslinking agent. Therefore, the melt viscosity of the resin itself does not become extremely high, and sufficient low-temperature fixability is secured.

The above-mentioned molecular weight distribution is a molecular weight distribution measured by gel permeation chromatography. In the molecular weight distribution, each of the low polymer component and the high polymer component has a maximum molecular weight within the above range. Has a value.

The vinyl copolymer in the present invention comprises a styrene monomer, an acrylic ester or a methacrylic ester monomer as a constitutional unit in order to obtain basic characteristics as a toner such as charging characteristics and pulverizability. Is preferred.

Specific examples of the styrene-based monomer include:
Other than styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-ter-butylstyrene, pn-
Hexyl styrene, pn-octyl styrene, pn
-Dodecyl methylene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like can be mentioned.

Specific examples of the acrylic acid ester or methacrylic acid ester monomer used in the present invention include:
Methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate,
N-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, methacrylic acid In addition to alkyl esters of acrylic acid or methacrylic acid such as dodecyl and stearyl methacrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate,
2-hydroxyethyl methacrylate, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, methacryloxyethyl phosphate and the like can be mentioned, and ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl mectalylate. , Propyl methacrylate, butyl methacrylate and the like are particularly preferably used.

Other vinyl monomers used in the present invention include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid and crotonic acid, and α- or β-alkyl derivatives thereof; fumaric acid and maleic acid. Unsaturated dicarboxylic acids such as acids, citraconic acid, itaconic acid and their monoester and diester derivatives; succinic acid monoacryloyloxyethyl ester, succinic acid monomethacryloyloxyethyl ester, acrylonitrile, methacrylonitrile, acrylamide, etc. it can.

The vinyl copolymer in the present invention is formed of at least a low polymer component having a peak at a low molecular weight and a high polymer component having a peak at a high molecular weight, and is usually used as a toner resin. It is not particularly limited as long as it is present, but the maximum value of the molecular weight distribution of the cross-linked low polymer component having a peak at a low molecular weight is 4 ×.
It is in the range of 10 ³ to 8 × 10 ⁴ .

The cross-linking agent used in the present invention is a diacrylate or dimethacrylate composed of a straight chain having 5 or more carbon atoms and a branched chain having 1 or less carbon atoms, and specific examples include triethylene glycol dimethacrylate. Methacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, ditetramethylene glycol dimethacrylate, polytetramethylene glycol dimethacrylate, 1,5 pentanediol dimethacrylate,
1,6 hexanediol dimethacrylate, 1,7 heptanediol dimethacrylate, 1,8 octanediol dimethacrylate, 1,9 nonanediol dimethacrylate, 1,10 decanediol dimethacrylate, polyethylene diol dimethacrylate, triethylene glycol diacrylate , Tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, ditetramethylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,5 pentanediol diacrylate, 1,6 hexanediol Diacrylate, 1,
7-heptanediol diacrylate, 1,8-octanediol diacrylate, 1,8-nonanediol diacrylate, 1,10-decanediol diacrylate, polyethylene diol diacrylate, neopentyl glycol hydroxybibalate, caprolactone modified hydroxypivalate neopentyl-glycol Examples thereof include acrylate and ECH-modified 1,6-hexanediol diacrylate. From the viewpoint of reactivity, etc., 1,5-pentanediol dimethacrylate, 1,6 are particularly preferred.
Hexanedidiol methacrylate, 1,5 pentanediol diacrylate, and 1,6 hexanediol diacrylate may be mentioned.

If the cross-linking agent has a straight-chain carbon number of 5 or less, is not straight-chain, has too long a branch chain, or uses a tri- or higher-functional cross-linking agent, the cross-linking density becomes too high. For this reason, the degree of freedom of the resin becomes low during melting. Therefore, the fluidity at the time of melting becomes low, fixing does not occur at low temperature, and it becomes difficult to disperse uniformly in the high polymer component, the dispersion becomes non-uniform, and the long-term image stability deteriorates.

The amount of the cross-linking agent used is 0.1 to 10% by weight, preferably 0.3 to 3% by weight, based on the polymer component having a peak at a low molecular weight. If it is less than 0.1% by weight, a sufficient effect cannot be obtained, and if it exceeds 10% by weight, the degree of cross-linking becomes too high, resulting in a low degree of freedom of the resin at the time of melting, resulting in poor fluidity and fixing at low temperature. If not, it becomes difficult to uniformly disperse with the high polymer component, the dispersion becomes non-uniform, and the long-term image stability deteriorates.

The high-polymer component which is not crosslinked and has a maximum molecular weight at a high molecular weight has a maximum molecular weight of 1
It is in the range of x10 ⁵ to 4x10 ⁶ . If it is smaller than this range, the offset resistance may deteriorate, and if it is larger than this range or if it is crosslinked,
Dispersion with the low polymer component becomes non-uniform, and long-term image stability decreases.

In the vinyl-based copolymer formed of the low molecular weight portion and the high molecular weight portion, if the content of the high polymer component is less than 10% by weight, the offset resistance may be deteriorated. Yes, and preferably 20% by weight or more. On the other hand, if it is 70% by weight or more, a sufficiently low fixing temperature may not be secured, and it is preferably 40% by weight or less.

Further, the vinyl copolymer of the present invention preferably has a glass transition point of 50 ° C. or higher from the viewpoint of cohesiveness. As a method for synthesizing a vinyl-based copolymer,
Suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization and the like can be used. The vinyl-based copolymer may be heat-melt blended, but it is preferable that the vinyl-based copolymer is dispersed in a solvent and then desolvated in order to make it more homogeneous. More preferably, the low molecular weight component is polymerized in the presence of the high molecular weight component.

In the resin composition for a toner of the present invention, vinyl acetate, vinyl chloride, ethylene and the like may be copolymerized with the vinyl-based copolymer within the range where the object of the present invention can be achieved. It does not matter if the polymer of the monomers is blended. Further, a polyester resin or an epoxy resin may be mixed. Further, aliphatic amide, bisaliphatic amide, metal soap, paraffin, etc. may be mixed.

The toner of the present invention contains the above resin composition for toner and a colorant as main components. That is, a toner can be provided by mixing the colorant described below with the above resin composition for toner.

Carbon black, chrome, yellow, aniline blue and the like can be used as the colorant. Further, in the toner of the present invention, a dye such as nigrosine, spirone black (manufactured by Hodogaya Chemical Co., Ltd.) or other phthalocyanine-based pigment can be added to the toner of the present invention as long as the object of the present invention can be achieved. .

Further, low-molecular-weight polyethylene, polypropylene wax or the like may be added as a release agent, or hydrophobic silica or the like may be added to enhance fluidity.

[0034]

The resin composition for a toner according to claim 1 contains a vinyl copolymer having the low polymer component and the high polymer component as a main component. Since the low polymer component is cross-linked by the cross-linking agent, the strength of the toner resin is increased. Therefore, the white background resistance is improved.

Further, since the molecular weight distribution of the low polymer component is widened by crosslinking the low polymer component, the dispersibility of the low polymer component in the high polymer component is enhanced. Therefore, the charge control agent can be more uniformly dispersed in the toner resin composition, and the stability of the image can be improved for a long period of time.

Further, since the low polymer component is gently cross-linked by the relatively long-chain cross-linking agent, the melt viscosity of the toner resin itself does not become extremely high. Therefore, it is possible to secure sufficient low temperature fixability.

A toner according to a fourth aspect of the invention contains the toner resin composition of the first aspect of the invention and a colorant. Therefore, the colorant is uniformly dispersed because it exhibits the same effect as that of the first aspect of the invention and the dispersibility of the toner resin composition is enhanced.

[0038]

As described above, according to the invention described in claim 1, in the resin composition for toner containing a vinyl-based copolymer as a main component, the vinyl-based copolymer has a relatively long chain. Since the low polymer component cross-linked by the cross-linking agent and the high polymer component not cross-linked are included, the resin strength can be increased, and thus a toner excellent in white background resistance can be provided. Further, since the dispersibility of the low polymer component into the high polymer component is enhanced, the charge control agent, the colorant, and the like can be more uniformly dispersed, and the stability of the image for a long time can be improved. It is possible to obtain a toner that can be formed and hardly aggregates. Further, since the low polymer component is gently cross-linked by the above-mentioned specific cross-linking agent, sufficient low-temperature fixability is secured.

Therefore, by using the resin composition for a toner according to the first aspect of the present invention, it is difficult to aggregate, is excellent in the offset resistance, the white background resistance and the low temperature fixing property, and can be used for a long time in a copying machine. It is possible to provide the toner of the invention described in claim 4, which is excellent in image stability when used in 1.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be clarified by describing non-limiting examples of the present invention. In the following, parts mean parts by weight unless otherwise specified.

Example 1 1000 g of toluene in a 3 liter separable flask
And 30 parts of 2-ethylhexyl acrylate are copolymerized with 70 parts of styrene, and the maximum value of the molecular weight is 60.
After adding 200 g of a copolymer, the gas phase was replaced with nitrogen gas while stirring, the system was heated to the boiling point of toluene.

With the reflux of toluene, with stirring, 780 g of styrene and 20 g of n-butyl methacrylate.
Solution polymerization was carried out while dropping a mixture of 0 g, 20 g of 1,6-hexanediol dimethacrylate as a cross-linking agent and 40 g of azobisisobutyronitrile as a polymerization initiator over 6 hours. After completion of dropping, the mixture was aged for 6 hours while stirring at the boiling temperature of toluene. Thereafter, while gradually raising the temperature of the system to 180 ° C., the solvent of toluene was removed under reduced pressure, further cooled and pulverized to obtain the resin A of the present invention in which the maximum molecular weight of the low polymer component was about 10,000. It was The glass transition point Tg of resin A is 60 ° C.
Met. The maximum molecular weight is a value obtained from the molecular weight distribution measured by gel permeation chromatography.

100 parts by weight of Resin A, 5 parts by weight of carbon black (MA-100: manufactured by Mitsubishi Kasei), 1 part by weight of Spiron Black TRH, and 3 parts by weight of polypropylene wax (Viscole 660P: manufactured by Sanyo Kasei). Melt blending, cooling, coarse pulverization, and fine pulverization with a jet mill to produce a toner powder having an average particle size of about 13 to 15 microns.

10 g of the obtained toner powder was placed in a 100 ml sample bottle, allowed to stand in a constant temperature bath at 50 ° C. for 16 hours, and the degree of coagulation was measured with a Bowder tester (manufactured by Hosokawa Micron Co.). There wasn't.

Also, 4 parts by weight of this toner powder is added to about 50-
A developer was prepared by mixing with 96 parts by weight of an iron powder carrier having an average particle size of 80 microns, and a copy was obtained using this developer. The electrophotographic copying machine used is D manufactured by Mita Kogyo Co., Ltd.
It is a modification of C-4085.

The minimum fixing temperature is set when the density of the copy image changes when the set temperature of the heat roller of the electrophotographic copying machine is variously changed and the obtained copy is rubbed with a sand eraser for a typewriter. Temperature. The minimum fixing temperature of the developer using the resin A was 150 ° C., which was sufficiently low.

The offset generation temperature is the temperature set when the offset occurs by variously changing the set temperature of the heat roller of the electrophotographic copying machine. The offset generation temperature of the developer using the resin A was 200 ° C. or higher, which was sufficiently high.

When halftone was copied using this developer, a uniform high-quality image was obtained. Furthermore, a running test was performed on 50,000 sheets, but no distortion of the halftone image was observed. I rubbed the halftone image with my finger and found almost no white background stains.

Example 2 1000 g of xylene was placed in a 3 liter separable flask.
Was charged, the gas phase was replaced with nitrogen gas, and then the system was heated to the boiling point of xylene.

With reflux of xylene, with stirring, 800 g of styrene, n-butyl acrylate 195
g, 1,5 pentanediol diacrylate as a cross-linking agent, and a mixture of 25 g of benzoyl peroxide as a polymerization initiator dissolved therein were added dropwise over 5 hours to perform solution polymerization. After the completion of the dropping, the mixture was aged for 5 hours while stirring at the boiling temperature of xylene. Then, while gradually raising the temperature of the system to 180 ° C., the xylene was removed under reduced pressure to reduce the maximum molecular weight to about 2
Million resins are obtained.

700 g of the obtained resin, 300 g of a resin having a maximum molecular weight of 1,000,000 obtained by polymerizing 20 parts of n-butyl acrylate with 80 parts of styrene, and 1000 g of xylene were mixed with 3 liters of separa. After putting in a bull flask and replacing the gas phase with nitrogen gas, this system was heated to the boiling point of xylene while stirring.

The mixture was stirred for 1 hour while xylene was refluxed. Then, while gradually raising the temperature of the system to 180 ° C., xylene was desolvated under reduced pressure, then cooled and pulverized to obtain Resin B of the present invention. Glass transition point T of resin B
The g was 62 ° C.

Resin B was used in place of resin A in Example 1.
A developer was prepared in the same manner except that the above was used and evaluated in the same manner. No cohesiveness was observed, the minimum fixing temperature was 150 ° C, and the offset generation temperature was 200 ° C or higher.

Further, when halftone was copied using this developer, a uniform high-quality image was obtained. When a running test was further performed on 50,000 sheets, Example 1 was performed.
Although it is slightly inferior to the toner of No. 1, the disorder of the halftone image was not seen. I rubbed the halftone image with my finger and found almost no stain on a white background.

Example 3 A developer was prepared and evaluated in the same manner as in Example 2 except that tetraethylene glycol diacrylate was used instead of 1,5 pentanediol diacrylate as the crosslinking agent. The maximum molecular weight of the low-polymer component of the obtained resin was about 20,000, and the Tg of the resin was 6
It was 0 ° C.

No cohesiveness was observed and the minimum fixing temperature was 15
The offset generation temperature was 0 ° C. and 200 ° C. or less. Further, when a halftone was copied using this developer, a uniform image was obtained although it was inferior to the toner of Example 2. Further, a running test was conducted on 50,000 sheets, but the toner of Example 2 was slightly inferior, but no disturbance of the halftone image was observed.

When the halftone image was rubbed with a finger, it was slightly inferior to the toner of Example 2, but almost no white background stain was observed.

Comparative Example 1 A developer was prepared and evaluated in the same manner as in Example 1 except that the crosslinking agent was not used. The obtained resin is about 1
It had a maximum molecular weight and had a Tg of 59 ° C.

No cohesiveness was observed and the minimum fixing temperature was 15
The offset generation temperature was 0 ° C. and 200 ° C. or higher. However, the uniformity of the halftone image was inferior to that of Examples 1 to 3, and the image was slightly distorted in the running test of 50,000 sheets. When rubbing the halftone image with a finger, white background stains were seen.

Comparative Example 2 A developer was prepared and evaluated in the same manner as in Example 1 except that 120 g of the polymerization initiator azobisisobutyronitrile was used instead of 40 g. The obtained resin is about 30
It had a maximum value of molecular weight at 00 and Tg of 42 ° C.

The fixing temperature was 130 ° C. and the offset generation temperature was 190 ° C., but cohesiveness was observed. In addition, the uniformity of the halftone image was inferior, and a slight disturbance of the image was clearly seen in the running test of 50,000 sheets.
When I rubbed the halftone image with my finger, there was a terrible stain on the white background.

Comparative Example 3 A developer was prepared and evaluated in the same manner as in Example 1 except that 4 g was used instead of 40 g of the polymerization initiator azobisisobutyronitrile. The obtained resin had a maximum molecular weight of about 100,000 and Tg of 65 ° C.

No cohesiveness was observed and the offset generation temperature was 200 ° C. or higher, but the minimum fixing temperature was as high as 180 ° C. The uniformity of the halftone image is poor and 5
Distortion of the image was clearly seen in the running test of 10,000 sheets. I rubbed the halftone image with my finger and found no stain on the white background.

Comparative Example 4 A developer was prepared and evaluated in the same manner as in Example 2 except that a resin having a maximum molecular weight of 1,000,000 was not used.
The obtained resin has a maximum molecular weight of about 20,000,
g was 60 ° C.

No cohesiveness was observed and the fixing temperature was 150 ° C.
Met. Halftone images have excellent uniformity and
The image was not disturbed even in the running test of 10,000 sheets, but the offset generation temperature was as low as 160 ° C. When the halftone image was rubbed with a finger, a slight white background stain was observed.

Comparative Example 5 A developer was prepared and evaluated in the same manner as in Example 2 except that divinyl benzene was used instead of 1,5 pentanediol diacrylate. The obtained resin had a maximum molecular weight of about 20,000 and Tg of 60 ° C.

No cohesiveness was observed and the offset generation temperature was 200 ° C. or higher, but the minimum fixing temperature was as high as 180 ° C. The uniformity of the halftone image is poor and 5
Distortion of the image was clearly seen in the running test of 10,000 sheets. When the halftone image was rubbed with a finger, no white background stain was found.

Comparative Example 6 A developer was prepared and evaluated in the same manner as in Example 2 except that pentaerythritol tetraacrylate was used instead of 1,5 pentanediol diacrylate. The obtained resin had a maximum molecular weight of about 20,000 and Tg of 60 ° C.

No cohesiveness was observed and the offset generation temperature was 200 ° C. or higher, but the minimum fixing temperature was as high as 170 ° C. The uniformity of the halftone image is poor and 5
Distortion of the image was clearly seen in the running test of 10,000 sheets. When the halftone image was rubbed with a finger, no white background stain was found.

Comparative Example 7 A developer was prepared and evaluated in the same manner as in Example 2 except that a resin having the same composition and a gel content of 90% was used instead of the resin having a maximum molecular weight of 1,000,000. . The obtained resin had a maximum molecular weight of about 20,000 and Tg of 60 ° C.

No cohesiveness was observed, and the offset generation temperature was 200 ° C. or higher, but the minimum fixing temperature was 160 ° C., which was higher than in the examples. The uniformity of the halftone image was inferior, and the image distortion was clearly seen in the running test of 50,000 sheets.

When the halftone image was rubbed with a finger, no white background stain was observed. The results of Examples 1 to 3 and Comparative Examples 1 to 7 are summarized in Table 1 below.

[0073]

[Table 1]

Claims (4)

[Claims] 1. A resin composition for a toner, which comprises a vinyl-based copolymer as a main component, wherein the vinyl-based copolymer is crosslinked and has a maximum molecular weight at a low molecular weight. And a high polymer component which is not crosslinked and has a maximum molecular weight in a high molecular weight, wherein the low polymer component has a straight chain having 5 or more carbon atoms and does not have a branched chain, Alternatively, it is cross-linked by a cross-linking agent composed of a diacrylate or dimethacrylate obtained from a diol having 1 or less carbon atoms in the branch chain, and the maximum molecular weight in the molecular weight distribution is in the range of 4 × 10 ³ to 8 × 10 ⁴ . The high-polymer component has a maximum molecular weight in the molecular weight distribution in the range of 1 × 10 ⁵ to 4 × 10 ⁶ , and the vinyl-based copolymer contains a styrene-based monomer as a main component, and (meth) Acrylic ester monomer and Or toner resin composition characterized in that as constituent units other vinyl monomers. 2. The cross-linking agent is a diacrylate or dimethacrylate obtained from a diol having a straight chain of 5 or more carbon atoms and having no branch chain, according to claim 1. Resin composition for toner. 3. The cross-linking agent is a diacrylate or dimethacrylate obtained from a diol having a linear aliphatic alkyl group having 5 or more carbon atoms and having no branch chain. Item 3. The toner resin composition according to Item 2. 4. A toner comprising, as a main component, a colorant and the resin composition for a toner according to claim 1.